Because when you're pals with Zac Efron, you have to be shirtless. The former Disney star showed off his ripped abs once again this week, but this time, while hanging out with his Mike and Dave Need Wedding Dates costar Adam DeVine. The hunky twosome went swimming at a lake in Oahu, Hawaii, on Sunday, June 14.

Efron, 27, wasn't shy about baring his toned body in blue swim trunks. He flexed his muscles, and used a rope to swing and jump into the water several times during the adventurous afternoon. His buddy DeVine, meanwhile, held on tight to a tire swing before getting soaked. He also threw his white T-shirt to the side while taking a photo with Efron.

"Here's to me being way more muscular and generally more shredded than my lil bro @zacefron," the Pitch Perfect 2 actor, 31, joked via Instagram on June 8. "In our off time we jump off waterfall's and nearly escape death. Nbd. Having so much fun shooting #mikeanddaveneedweddingdates this summer in Hawaii!"